PHP 8.0 polyfills for testing purposes

Author: ondrejmirtes

Diff for: composer.json

@@ -32,6 +32,7 @@
     "symfony/framework-bundle": "^4.4 || ^5.0",
     "symfony/http-foundation": "^5.1",
     "symfony/messenger": "^4.2 || ^5.0",
+    "symfony/polyfill-php80": "^1.24",
     "symfony/serializer": "^4.0 || ^5.0"
   },
   "config": {